WEDNESDAY, July 31 (HealthDay News) -- Type 2 diabetes patients with dangerously low blood sugar levels may be at increased risk for cardiovascular disease, according to a new study.

Given their findings, "less stringent glycemic targets may be considered for type 2 diabetic patients at high risk of hypoglycemia (severely low blood sugar)," the researchers said.

A dangerously low blood sugar level often is classified as a medical emergency. Previous observational studies have reported a link between severe hypoglycemia and cardiovascular disease risk, but the association remains controversial.

In this study, researchers from the United States, Japan and the Netherlands analyzed the findings of six studies that included a total of more than 903,000 type 2 diabetes patients.

The review revealed that 0.6 percent to 5.8 percent of patients developed severe hypoglycemia during one to five years of follow-up. Overall, these patients had a 1.56 percent increased risk of developing cardiovascular disease, according to the study, which was published July 30 in the online journal BMJ.com.

The results suggest that severe hypoglycemia is associated with a two-fold increased risk of cardiovascular disease, the researchers said.

Because of this, preventing severe hypoglycemia in people with type 2 diabetes may be important to prevent cardiovascular disease, the researchers said in a journal news release.

The link between severe hypoglycemia and increased cardiovascular disease risk has previously been explained by patients having one or more other serious illnesses, but this is an unlikely explanation, the researchers said.

They said the incidence of serious illnesses would need to be "unrealistically high" among patients who developed severe hypoglycemia, and the link between serious illnesses and cardiovascular disease would have to be "extremely strong."